Coil spring rail brake

ABSTRACT

A rail brake includes a rigid enclosure which mounts under a crane so as to dispose the base end of the enclosure over and adjacent a rail. A top plate is mounted underneath the upper end of the enclosure. A spring carriage is mounted for vertical translation within the enclosure, beneath the top plate. Springs are mounted between the spring carriage and the top plate so that the springs are compressed when the spring carriage is elevated. A brake shoe is mounted under the carriage. Actuators are mounted between the spring carriage and the base end of the enclosure. Extension of the actuators compress the springs and elevate the brake shoe from the rail. Retraction allows the springs to drive the brake shoe against the rail. An opening in the enclosure allows replacement of the springs and actuators. Elevation of the brake shoe provides for its inspection and maintenance.

FIELD OF THE INVENTION

This invention relates to the field of rail brakes and in particular toan improved coil spring rail brake which provides, among other things,for improved access to the spring assembly and to the brake shoes forease of maintenance and repair.

BACKGROUND OF THE INVENTION

In the prior art, applicant is aware of various designs of rail brakes.In particular, applicant is aware of the following U.S. patents:

U.S. Pat. No. 581,270 which issued Apr. 27, 1897, to Davis for a RailBrake discloses the use of coil springs secured to lever bars so as tohold the lever bars, and the brake shoes mounted thereunder, away fromthe track rails.

U.S. Pat. No. 1,790,202 which issued to Down on Jan. 27, 1931, for aMagnetic Brake Device, discloses a magnetic brake shoe which is normallyheld suspended away from the rail and, upon energization, is attractedto the rail to act as a brake. A coil spring is disposed in a chamberand acts on a piston so as to normally maintain the brake shoe in asuspended position over the rail.

U.S. Pat. No. 3,878,925 which issued to Ignatoweicz in Apr. 22, 1975,for a Mounting Device for Magnetic Rail Brakes, discloses reducing theair pressure in conventional bellows so as to compress the bellowsdownwardly until stopped by a spring buffer at a low position whereinthe brake magnet may be energized so as to be attracted towards the railthereby causing a further compression of the spring buffer. Correctionof the vertical setting of the magnetic brake unit is accomplished bypressurizing the bellows so as to raise the magnetic unit to a highposition. The height of the magnetic unit above the rail may then beadjusted.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a rail brake inwhich at least one or more of the following characteristics are present:

-   -   a) the rail brake brake shoes may be replaced without removing        the whole rail brake assembly from the crane or other        rail-mounted machine having the rail brake mounted thereon.    -   b) the rail brake actuators may be removed for service without        removing the rail brake assembly from the crane or other        rail-mounted machine having the rail brake, both when the brake        is applied or when the brake is released and the rail brake        springs are caged;    -   c) the springs, when caged, together with the top plate may be        removed modularly from the rail brake enclosure without removing        the enclosure from the crane or other rail-mounted machine.

The rail brake according to the present invention includes a rigidenclosure having an upper end and opposite base end rigidly mountedoppositely to the upper end. The upper end is adapted for mounting tothe rail-mounted machine, for example under a crane, so as to disposethe base end of the enclosure over and adjacent the rail. A top plate ismounted underneath the upper end of the enclosure, spaced apart from andsubstantially parallel to the upper end of the enclosure so as to definea gap there-between.

A spring carriage is mounted for vertical translation within theenclosure, beneath the top plate, between an elevated position and alowered position. At least one spring is mounted between the springcarriage and the top plate so that the springs are compressed when thespring carriage is in its elevated position and decompressed when thespring carriage is in its lowered position. At least one brake shoe ismounted under the carriage so as to be oppositely disposed on thecarriage relative to the springs.

At least one selectively actuable actuator is mounted between, so as tobear opposite ends thereof against, the spring carriage and the base endof the enclosure respectively. The actuators are actuable betweenextended and refracted positions. In the extended position, the springcarriage is in its elevated position and the brake shoes arecorrespondingly retracted upwardly. In the retracted position, thespring carriage is in its lowered position and the brake shoes arecorrespondingly lowered so as to be urged by the springs into frictionalengagement against the rail.

The enclosure includes sides extending between the upper end and thebase end. At least one of the sides is open for ease of removal of thespring carriage, the top plate, the springs and/or the actuatorstherethrough.

The spring carriage may also include an elongate caging member, wherethe caging member has opposite first and second ends. The caging memberis mounted to the spring carriage at the first end of the member andextends substantially parallel to the springs. The second end of themember is journalled upwardly through an aperture in the top plate, andis free to translate vertically in the gap as the spring carriagetranslates correspondingly within the enclosure so as to translatesimultaneously and correspondingly therewith. The second end of thecaging member protrudes into a spring-caging position in the gap whenthe spring carriage is in its elevated position.

A selectively releasable lock locks the second end of the caging memberin its spring-caging position whereby translation of the caging memberand the spring carriage is immobilized. The lock may include a latchmember in which case the caging member includes a latch receiver forreleasably holding the latch member when caging member is in itsspring-caging position. The brake shoes are removable when the springcarriage is in its elevated position.

In a preferred embodiment the spring carriage also includes bearingmembers corresponding to the location of the tops of the actuators sothat the actuators bear against the bearing members. The bearing membersmay include a pair of substantially oppositely disposed bearing membersextending orthogonally relative to the actuators. The actuators may becorresponding pair of actuators extending substantially parallel to thesprings.

The carriage translates a brake set distance between the elevated andlowered positions, and the actuators actuate a corresponding actuationdistance between their extended and retracted positions. The actuatorsalso selectively elevate the spring carriage to an unlocking positionwhich is further elevated above the carriage's elevated position so asto unload a spring force load applied to the latch member of the latchreceiver. Once the spring force is unloaded the latch member isremovable from the latch receiver.

The latch member may include a fork, in which case the latch receiverincludes a lip on the caging member. The lip may be a substantiallyannular lip. The lip may be formed by a collar on the caging member. Thelatch member may be elongate and mounted substantially horizontally forhorizontal translation into engagement under the lip.

In one embodiment, spacers define a vertical separation distance withinthe gap between the upper end of the enclosure and the top plate. Thevertical separation distance is substantially equal to the translationdistance of the spring carriage between it's lowered position and it'selevated position. The separation distance may be substantially equal toa translation distance of the spring carriage between it's loweredposition and it's unlocking position when the caging members are furtherelevated to allow unlocking of the corresponding latches.

The springs may be a pair of helical coil springs and the caging membersmay be a pair of elongate shafts. The elongate shafts may be journalledthrough corresponding springs.

The brake shoes may be mounted under the carriage substantiallyequi-distant, when measured horizontally between the pair of springs soas to substantially evenly distribute a downward spring force of thesprings to the brake shoes.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings forming part of this specification, like referencenumerals denote corresponding parts in each view, and wherein:

FIG. 1 a is, in partially cut-away side elevation view, one embodimentof the coil spring rail brake according to the present invention.

FIG. 1 b is, in front elevation view, the rail brake of FIG. 1 a.

FIG. 1 c is, in plan view, the rail brake of FIG. 1 a.

FIG. 2 a is, in partially cut-away side elevation view, the rail brakeof FIG. 1 a with the pair of helical coil springs removed and showingthe rail brake housing.

FIG. 2 b is, in front elevation view, the rail brake of FIG. 2 a.

FIG. 2 c is, in plan view, the rail brake of FIG. 2 a.

FIG. 3 a is the rail brake of FIG. 1 b mounted to a rail-mounted machineso as to be suspended over a rail, with the brake released.

FIG. 3 b is the rail brake of FIG. 3 a in the brake set position atnominal rail height.

FIG. 3 c is the rail brake of FIG. 3 b with the rail brake in a brakeset position at a rail deviation of +2 mm.

FIG. 3 d is the rail brake of FIG. 3 c with the rail brake in a brakeset position at a rail deviation of −2 mm.

FIG. 3 e is the rail brake of FIG. 3 a with the springs caged.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The rail brake according to the present invention is mounted under arail-mounted machine such as a crane 10. There exists a space betweenthe crane and the rails in which a rigid enclosure is mounted. The topplate of the enclosure is bolted to the underside of the crane so as toposition the bottom of the enclosure adjacent the rail to which thebrake is to be applied. A modular spring and actuator mechanism ishoused in the enclosure. The springs and/or actuators may be removedfrom the enclosure for servicing, as better described below, through anopening in the enclosure. In a preferred embodiment of the actuators area pair of actuators mounted in the enclosure to act on the springmechanism. The spring mechanism includes a pair of helical coil springs12 which in one embodiment exert a nominal 470 kilo-newton downwardforce driving downwardly one or more brake shoes 14 mounted under thespring mechanism. In particular, brake shoes 14 mounted on shoe rods 16are driven downwardly into frictional engagement against the uppersurface of rails 18. Brake shoes 14 are mounted to shoe rods 16 by bolts16 a engaging through holes in metal clips 16 b, thereby allowing wornbrake shoes to be replaced without removing the enclosure or any partthereof from the crane once the brake shoes have been elevated above therail.

Within the spring mechanism, coil springs 12 are maintained in spacedapart parallel alignment by rigid supports mounted to contain the topsand the bottoms of the springs and in particular by a spring holder 20supporting the bottom of the springs and by a top plate assembly 22supporting the tops of the springs. Spring holder 20 includes walls 20 aformed to cup the bottoms of the springs 12 and vertically upstandingcylindrical caging members or guides 20 b which extend upwardly withinthe cavity defined by walls 20 a so that, with springs 12 installed inspring holder 20, guides 20 b extend upwardly journalled through thecenter of the helical coils of the springs. The top surfaces of guides20 b are adjacent the underside of top plate assembly 22 when thesprings 12 are fully compressed as further described below. A centerguide member 20 c extends upwardly between the springs and acts as astop against top plate assembly 22 to prevent over-compressing of thesprings as over-compression of the springs may damage the springs. Thetop of center guide member 20 acts as a spacer in combination with thetop plate to prevent this over-compression.

A caging pin 24 is rigidly mounted into the top ends of guides 20 b soas to protrude vertically upwards therefrom. The shank 24 a of pins 24pass through corresponding apertures 22 a formed in top plate assembly22 so that as springs 12 are compressed or allowed to expand, cagingpins 24 mounted in guides 20 b are raised or lowered respectivelyrelative top plate assembly 22.

Springs 12 and the supports for the springs provided by a springcarriage such as spring holder 20 are all mounted within a rigidenclosure 26. Enclosure 26 is mounted to the underside of therail-mounted machinery, such as the underside of crane 10, in the spacebetween the underside of the machine and the rail. Top plate assembly 22is bolted to spacers 22 b mounted underneath the upper plate 26 a ofenclosure 26. Enclosure 26 includes upper plate 26 a, sidewalls or asupporting framework 26 b (collectively referred to herein as walls),and a rigid base 26 c supported rigidly underneath the upper plate 26 aby the walls. The spring assembly which consists of the pair of springs12, the spring holder 20, and the top plate assembly 22, is mountedwithin the enclosure 26 so that the spring assembly may be removed froman opening in the side of the enclosure, that is, through an opening ina wall of the enclosure, once the brake shoe assembly has been removedand the spring top plate assembly 22 unbolted from the spacers 22 bunder upper plate 26 a by removing bolts 30.

A cavity or space 28 is maintained between top plate assembly 22 and theupper plate 26 a of enclosure 26 by spacers 22 b. Space 28 allows forvertical translation of caging pins 24, that is, of the upper end of thecaging members. With the top plate assembly 22 bolted to the upper plate26 a by bolts 30 through spacers 22 b, the spring assembly is suspendedwithin enclosure 26 so as to accommodate the compression and extensionof springs 12. As springs 12 extend, spring holder 20 is pusheddownwardly so as to bias brake shoe 14 downwardly into frictionalengagement on rail 12. A pair of actuators 32, which may be hydraulicactuators, are mounted between the base 26 c of the enclosure andbearing members such as a cantilevered or otherwise formed pair of rigidflanges 20 c extending laterally from spring holder 20. When actuated soas to extend the actuator pistons, actuators 32 drive spring holder 20upwardly. This compresses springs 12 towards their fully compressedcaged position and elevates the brake shoes 14 above rail 18. As springholder 20 is elevated, caging pin 24 is also elevated so as to raisehead 24 b on shank 24 a into space 28 above the corresponding uppersurface of top plate assembly 22.

With the springs fully compressed by the actuators, for example given anactuator piston stroke of approximately 10 mm, head 24 b will also beelevated by the same stroke into space 28 above the corresponding uppersurface of top plate assembly 22. A lock or latch, for example includinga latch member such as fork 34 having a thickness substantially equal tothe stroke distance is mounted horizontally for lateral slidingtranslation so as to place the tines 34 a of the fork under the annularlip of head 24 b of the caging pin. Head 24 b may be formed to includean annular lip, rim or collar to engage the fork tines. Fork 34 may bemanually actuated by means of for example a handle or pin 34 b. Pin 34 bis pushed horizontally to insert fork 34 under head 24 b when springs 12are fully compressed. The insertion of the tines 34 b of fork 34 underhead 24 b cages springs 12 so as to park the brake shoes in a positionelevated above rail 18. The brake shoes may then be removed forinspection, maintenance, or replacement. To release the brake shoes fromtheir elevated and parked position, the actuators are fully extended soas to further slightly compress springs 12 to an unlock position, forexample a further 2 mm beyond the 10 mm nominal piston stroke, therebyunloading the spring force load from fork 34 by slightly elevating head24 b from fork 34. Fork 34 may then be extracted from underneath head 24b. The actuator pistons may then be retracted to allow springs 12 toextend by the piston stroke distance so as to engage the brake shoeagainst the rail.

In the above example which is not intended to be limiting, and asillustrated in FIGS. 3 a-3 e, given of a nominal piston stroke distanceof 10 mm, once the springs are compressed by the 10 mm stroke distance,a further available compression distance, for example a further 2 mm ofcompression is available so as to release fork 24 from under head 24 bof the caging pin. Also, when the springs are extended the strokedistance of for example 10 mm, the springs should also be capable of afurther extension of for example 2 mm so as to accommodate fluctuationsin the elevation of rail 12 relative to the elevation of enclosure 26.Thus for example within a range of plus or minus 2 mm the brake shoeshould be capable of vertical translation while still maintaining adownward force on the rail sufficient to provide the braking function toinhibit movement of the machine along the rail. To give one example ofthe force exerted by the springs, which example is not intended to belimiting, each spring may provide a nominal force of 270 kilo-newtonswith a maximum force of approximately 300 kilo-newtons. The pair ofsprings thus provides a nominal 540 kilo-newton force. Thus for the twosprings the force required to be exerted upwardly by the two actuatorsin order to compress the springs is a nominal 540 kilo-newtons and amaximum of approximately 600 kilo-newtons. The full compression of thesprings corresponds to the brake released position of the springassembly as seen in FIG. 3 a where the brake shoe is elevated 10 mmabove the rail and with the spring compressed by the 10 mm pistonstroke, that is almost to its maximum, for a spring length of 330 mm inthe example illustrated.

In the embodiment illustrated, in the brake release position theenclosure and spring assembly are sized so as to provide a 17 mm gap “a”between the bottom of spring holder 20 and the base 26 c of theenclosure, a gap “c” of 4 mm between the top of caging pin 24 and theunderside of upper plate 26 a, a fully extended position extension “d”of 23 mm, and 57 mm stand-off distances “f” and “g” respectively betweenthe bottom of base 26 c and the top of rail 12, and between the bottomof upper plate 26 a and the top of top plate assembly 22.

In the brake set position of FIG. 3 b the springs have been extended bythe nominal stroke distance of 10 mm by the retraction of the actuatorpistons, so as to provide a combined downward spring force of 540kilo-newtons pressing the brake shoe against the rail.

Thus gap “a” has been reduced to 7 mm, the spring length “b”correspondingly extended to 340 mm, gap “c” extended to 14 mm, thecylinder piston extension “d” reduced to 13 mm, the gap “e” between therail and the brake shoe reduced to nominally zero while the stand-offdistances “f” and “g” remain the same at 57 mm each. The holding forceof the rail brake is a function of the coefficient of friction betweenthe brake shoe and the rail. For a hardened, serrated brake shoe thecoefficient of friction may be a nominal 0.5 thus providing a holdingforce along the rail of a nominal 270 kilo-newtons.

FIG. 3 c illustrates the brake set position in the instance where, forexample, the rail elevation has deviated 2 mm upwardly so that insteadof the 10 mm stroke at the nominal rail height the spring travel isinstead 8 mm so that gap “a” is 9 mm, spring length “b” is 338 mm, gap“c” is 12 mm, and cylinder piston extension “d” is 15 mm, with the brakeshoe elevation being offset upwardly by 2 mm to account for thedeviation in the height of the rail. In this position, the spring forceis approximately 484 kilo-newtons.

FIG. 3 d illustrates the opposite example from FIG. 3 c in that itillustrates a brake set position where the rail deviation is 2 mm belowthe nominal rail height so that the spring travel is 12 mm instead ofthe nominal 10 mm. Thus gap “a” is 5 mm, spring length “b” is 342 mm,gap “c” is 16 mm, and cylinder piston extension “d” is 11 mm. The totalspring force between the two springs is approximately 456 kilo-newtons.In this example, the maximum working stroke of the springs is 16 mm andthe enclosure is sized so that the spring assembly bottoms out withinthe enclosure at 17 mm of stroke.

In the spring caged position of FIG. 3 e, fork 34 has been insertedunder head 24 b of caging pin 24 and the actuators 30 retracted so as toallow springs 12 to re-extend by 2 mm for a spring length “b” of 332 mmto thereby cage the springs by engaging the head of the caging pin downagainst the fork. Thus gap “a” is reduced to 15 mm and gap “c” isincreased to 6 mm as cylinder piston extension “d” is retracted forexample to a retracted extension of 6 mm.

As will be apparent to those skilled in the art in the light of theforegoing disclosure, many alterations and modifications are possible inthe practice of this invention without departing from the spirit orscope thereof. Accordingly, the scope of the invention is to beconstrued in accordance with the substance defined by the followingclaims.

1. A rail brake for a rail-mounted machine mounted for translation alonga rail, said rail brake comprising: a rigid enclosure having an upperend and opposite base end rigidly mounted oppositely to said upper end,wherein said upper end is adapted for mounting to the rail-mountedmachine so as to dispose said base end over and adjacent the rail, a topplate mounted underneath, spaced apart from and substantially parallelto, said upper end so as to define a gap between said upper end and saidtop plate. a spring carriage mounted for vertical translation withinsaid enclosure, beneath said top plate, between an elevated position anda lowered position, at least one spring mounted between said springcarriage and said top plate, said at least one spring compressed whensaid spring carriage is in said elevated position and decompressed whensaid spring carriage is in said lowered position, at least one brakeshoe mounted under said carriage so as to be oppositely disposed on saidcarriage relative to said at least one spring, at least one selectivelyactuable actuator mounted between, so as to bear opposite ends thereofagainst, said spring carriage and said base end of said enclosurerespectively, said at least one actuator actuable between extended andretracted positions wherein, in said extended position, said springcarriage is in said elevated position and said at least one brake shoeis correspondingly retracted upwardly, and wherein, in said retractedposition, said spring carriage is in said lowered position and said atleast one brake shoe is correspondingly lowered so as to be urged intofrictional engagement against the rail.
 2. The brake of claim 1 whereinsaid at least one spring is at least one helical coil spring, andfurther comprising an elongate caging member, said caging member havingopposite first and seconds ends, said member mounted to said springcarriage at said first end of said member and extending substantiallyparallel to said at least one spring, said second end of said memberjournalled in an aperture in said top plate, wherein said second end ofsaid member is free to translate vertically in said gap as said springcarriage translates correspondingly within said enclosure so as totranslate simultaneously and correspondingly therewith and so that saidsecond end of said member protrudes into a spring-caging position insaid gap when said spring carriage is in said elevated position, aselectively releasable lock selectively releasable locking said secondend of said caging member in said spring-caging position wherebytranslation of said caging member and said spring carriage isimmobilized when said second end is locked by said lock.
 3. The brake ofclaim 2 wherein said enclosure includes sides extending between saidupper end and said base end, and wherein at least one of said sides isopen for removal of said spring carriage, said top plate, said at leastone spring and/or said at least one actuator therethrough.
 4. The brakeof claim 3 wherein said at least one brake shoe is removable when saidspring carriage is in said elevated position.
 5. The brake of claim 4wherein said carriage includes at least one bearing member and whereinsaid at least one actuator bears against said at least one bearingmember.
 6. The brake of claim 5 wherein said carriage translates a brakeset distance between said elevated and lowered positions, and whereinsaid at least one actuator actuates a corresponding actuation distancebetween said extended and retracted positions.
 7. The brake of claim 6wherein said lock includes a latch member and wherein said caging memberincludes a latch receiver for releasably holding said latch member whensaid caging member is in said spring-caging position.
 8. The brake ofclaim 7 wherein said at least one actuator also selectively elevatessaid carriage to an unlocking position which is further elevated abovesaid elevated position so as to unload a spring force load applied tosaid latch member by said latch receiver, wherefrom said latch member isremovable from said latch receiver.
 9. The brake of claim 8 wherein saidlatch member includes a fork and wherein said latch receiver includes alip on said caging member.
 10. The brake of claim 9 wherein said lip isa substantially annular lip.
 11. The brake of claim 10 wherein said lipis formed by a collar on said caging member.
 12. The brake of claim 9wherein said latch member is elongate and mounted substantiallyhorizontally for horizontal translation into engagement under said lip.13. The brake of claim 7 further comprising at least one spacer defininga vertical separation distance within said gap between said upper endand said top plate.
 14. The brake of claim 13 wherein said separationdistance is substantially equal to a translation distance of said springcarriage between said lowered position and said elevated position. 15.The brake of claim 14 wherein said separation distance is substantiallyequal to a translation distance of said carriage between said loweredposition and said unlocking position when said at least one cagingmember is further elevated to allow unlocking of said latch.
 16. Thebrake of claim 15 wherein said at least one spring is a pair of helicalcoil springs and wherein said at least one caging member is a pair ofelongate shafts wherein each shaft of said pair of elongate shafts isjournalled through a corresponding spring of said pair of helical coilsprings.
 17. The brake of claim 16 wherein said latch member includes afork and wherein said latch receiver includes a lip on said cagingmember.
 18. The brake of claim 17 wherein said at least one bearingmember includes a pair of substantially oppositely disposed bearingmembers extending orthogonally relative to said pair of helical coilsprings, wherein said at least one actuator is a corresponding pair ofactuators extending substantially parallel to said pair of helical coilsprings.
 19. The brake of claim 18 wherein said at least one brake shoeis mounted under said carriage substantially equi-distant between saidpair of helical coil springs so as to substantially evenly distribute adownward spring force of said each spring to said at least one brakeshoe.